The balance between countryside and city has shifted decisively. Urbanization is the process by which an increasing proportion of a population comes to live in urban areas. It involves both the growth of existing cities and the creation of new ones.

Industrialization, rural–urban migration, and natural increase within cities drive the process. Urbanization transforms land use, social organization, and environmental footprints. In many developing countries the pace has been extremely rapid, outstripping infrastructure and housing supply.

Urbanization can foster economic opportunity and access to services, yet it also concentrates poverty and pollution if poorly managed. Planners seek compact, connected, and inclusive urban forms. The global urban transition is one of the major geographic shifts of the modern era.

• Rising share of population living in cities
• Driven by migration and urban growth
• Transforms land use and society
• Major global demographic trend